Edexcel GCSE Combined Science key terms

A particle smaller than an atom that forms part of its structure, such as a proton, neutron or electron.

A change directly from solid to gas, without passing through the liquid state.

A small number written at the lower right of a chemical symbol or bracket, showing how many of the preceding atom or group are present.

A substance that an enzyme acts on.

The amount of substrate in a given volume of solution.

The surface area of an object divided by its volume. Smaller pieces of the same material have a larger surface area to volume ratio.

The surface area of an organism or object compared with its volume, calculated by dividing surface area by volume.

Water flowing over the land surface towards streams, rivers, lakes and the sea.

Everything outside the reacting system that can exchange energy with it.

How likely an individual is to develop a disease.

A junction between neurones containing a tiny gap across which neurotransmitters transfer the signal.

The building of larger molecules from smaller molecules.

An object or group of objects chosen for study.

A straight line that touches a curve at a chosen point and has the same gradient as the curve at that point.

An organ containing cells that respond to a particular hormone.

A measure of how readily a material transfers energy by conduction. A material with lower thermal conductivity is a better thermal insulator.

A method of forming an image using infrared radiation emitted by objects, revealing differences in temperature.

A material or arrangement that reduces unwanted energy transfer by heating.

The distance a vehicle travels during the driver's reaction time, before braking begins.

A hormone produced by the thyroid gland that controls the body's metabolic rate.

Damage to a group of living cells, which can impair how a tissue works.

A method of finding the volume of one solution needed to react completely with a measured volume of another solution.

The volume of solution delivered from a burette during a titration, calculated as final reading minus initial reading.

Describes a poisonous substance that can cause serious harm or death.

How harmful a substance is to cells or an organism.

A device that uses electromagnetic induction between two coils to change the size of an alternating voltage.

The transport of sucrose around a plant through phloem.